I'm thinking about getting another PR chassis and opening up the PT cutout to accept a Tremolux/Vibroverb transformer, and then building out a single channel AB763 minus vibrato with Tung-Sol 5881s. I've already started working on a layout for the board. I'll probably use a 5U4GB to keep the voltage down. OT would either be a Bassman/Super type or Tremolux/Vibroverb/Pro sized, depending on which will fit over on the preamp side of the chassis. The baffle in my PR cabinet has an offset 12" cutout, so I'm not sure the bigger OT will fit.